Rhododendron groenlandicum (Labrador Tea)

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Rhododendron, Genus, groenlandicum, Species,

Genus & species

labrador tea

Ericaceae

Northern North America: Greenland to Pennsylvania, west to Cascades

Attracts Pollinators Deer Resistant Fragrant (strong)Container Friendly

SunFull Sun – Part Shade

WaterHigh

HardinessZones 2–7

Overview

Rhododendron groenlandicum is a small evergreen shrub reaching 1-5 feet (30-150 cm) tall and 2-4 feet (60-120 cm) wide, forming low loose mounds in cold bogs and acidic forest understories. Leaves are alternate, leathery, and aromatic when crushed, 1-2 inches (2.5-5 cm) long with rolled-under margins; the upper surface is dark green and the lower surface bears a dense rust-orange to white woolly indumentum that turns rusty with age. Flowers are white to creamy white, 0.3-0.5 inches (8-13 mm) across, in flat-topped terminal clusters of 15-30, opening from May through July. Fruits are dry capsules 0.2-0.3 inches (5-8 mm) long that split open from the base in late summer, releasing minute wind-dispersed seeds. Stems are slender and woody, with younger growth covered in red-brown hairs that fade to grey on second-year wood. Plants grow slowly, adding 2-4 inches (5-10 cm) per year on bog substrates. Roots are shallow and depend on ericoid mycorrhizal partners; cultivation in standard garden soil without acid amendment usually fails within 1-2 years. All parts contain grayanotoxins; ingestion causes salivation, vomiting, and cardiac symptoms in livestock and pets.

Native Range

Native across northern North America from Greenland and the Canadian Arctic south to the northern Great Lakes states, New England, the northern Rockies, and the Cascades, with isolated populations in Pennsylvania and northern New Jersey. Grows in sphagnum bogs, muskeg, peat fens, wet coniferous forests, and tundra at 0-7,000 feet (0-2,100 m) elevation.

Suggested Uses

Used in bog gardens, native plant collections, acid-soil borders, and ericaceous shrub plantings in zones 2-7. Spaced 3-4 feet (90-120 cm) apart in mass plantings on mounded peat. Not suited to alkaline-soil regions, hot interior valleys, or standard mixed perennial borders without significant soil amendment.

How to Identify

Identified by leathery evergreen leaves with strongly rolled-under margins and a dense rust-orange or white wool on the underside, white flat-topped flower clusters of 15-30 small flowers, and a sharply aromatic scent when leaves are crushed. Distinguished from Kalmia polifolia (bog laurel) by white (versus pink) flowers, woolly leaf undersides, and alternate (versus opposite) leaves. Distinguished from R. tomentosum by broader leaves and a North American range.

Appearance

Size & Dimensions

Height1' - 5'

Width/Spread2' - 4'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~3 weeks

Flowers: May–July

Spring Summer

May through July across the range; begins late April in zone 7 coastal bogs and extends into early August above the Arctic Circle. Individual flowers last 5-7 days; total bloom period at the shrub level lasts 2-3 weeks. Bloom timing is closely tied to spring thaw and varies by 4-6 weeks across the latitudinal range.

Detailed Descriptions

Flower Description

White to creamy white

Foliage Description

Dark green above, rust-orange to white woolly beneath

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-8 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range4.0 - 5.5 (Acidic)

3579

Soil Types

peat loam

Drainagemoist

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Care & Maintenance

Care Guide

Establish in acidic, peat-rich, consistently moist soil at pH 4.0-5.5; standard garden loam at neutral pH causes chlorosis and decline within 1-2 years. Top-dress annually with sphagnum peat, pine needles, or composted oak leaves to maintain organic content and acidity. Plants tolerate seasonal flooding but die in compacted heavy clay or in alkaline irrigation water. Heat above 85 degrees F (29 C) for extended periods causes leaf scorch in zones 7-8; container-grown plants in those zones require afternoon shade. Few pests trouble the species in its native range, but root weevils notch leaf margins on cultivated plants in the Pacific Northwest. All parts contain grayanotoxins; ingestion of leaves or honey from R. groenlandicum pollen causes nausea, salivation, and cardiac arrhythmia in livestock, pets, and humans.

Pruning

Cut tip-damaged or dead stems back to live wood in early spring before new growth begins. Light shaping is performed immediately after bloom; later pruning removes the following season's flower buds, which form on the previous season's wood. Mature plants in suitable sites need little pruning beyond removal of dead tips.

Pruning Schedule

Prune: July–August

summer